feat(ios): add Share Extension startup diagnostic marker and API

Write shareExtensionLastStart on ShareViewController.viewDidLoad and
expose getShareExtensionDiagnostics() through SharedImagePlugin with
shareId, file path, and fileExists for debugging failed share flows.

ios/App/App/SharedImagePlugin.swift

@@ -24,7 +24,8 @@ public class SharedImagePlugin: CAPPlugin, CAPBridgedPlugin {
     public var pluginMethods: [CAPPluginMethod] {
         return [
             CAPPluginMethod(#selector(getSharedImage(_:)), returnType: .promise),
-            CAPPluginMethod(#selector(hasSharedImage(_:)), returnType: .promise)
+            CAPPluginMethod(#selector(hasSharedImage(_:)), returnType: .promise),
+            CAPPluginMethod(#selector(getShareExtensionDiagnostics(_:)), returnType: .promise)
         ]
     }
     
@@ -62,5 +63,12 @@ public class SharedImagePlugin: CAPPlugin, CAPBridgedPlugin {
             "hasImage": hasImage
         ])
     }
+
+    /**
+     * Diagnostic snapshot of Share Extension startup and pending share state
+     */
+    @objc public func getShareExtensionDiagnostics(_ call: CAPPluginCall) {
+        call.resolve(SharedImageUtility.getShareExtensionDiagnostics())
+    }
 }
 

ios/App/App/SharedImageUtility.swift

@@ -14,6 +14,7 @@ public class SharedImageUtility {
     private static let sharedPhotoFileNameKey = "sharedPhotoFileName"
     private static let sharedPhotoFilePathKey = "sharedPhotoFilePath"
     private static let sharedPhotoShareIdKey = "sharedPhotoShareId"
+    private static let shareExtensionLastStartKey = "shareExtensionLastStart"
     private static let sharedPhotoReadyKey = "sharedPhotoReady"
     
     /// Get the App Group container URL for accessing shared files
@@ -97,6 +98,41 @@ public class SharedImageUtility {
         return FileManager.default.fileExists(atPath: fileURL.path)
     }
 
+    /**
+     * Diagnostic snapshot of Share Extension startup and pending share state
+     * Read-only: does not modify App Group storage
+     */
+    static func getShareExtensionDiagnostics() -> [String: Any] {
+        guard let userDefaults = UserDefaults(suiteName: appGroupIdentifier) else {
+            return [
+                "shareExtensionLastStart": NSNull(),
+                "sharedPhotoShareId": NSNull(),
+                "sharedPhotoFilePath": NSNull(),
+                "fileExists": false
+            ]
+        }
+
+        let shareExtensionLastStart = userDefaults.string(forKey: shareExtensionLastStartKey)
+        let shareId = userDefaults.string(forKey: sharedPhotoShareIdKey)
+        let filePath = userDefaults.string(forKey: sharedPhotoFilePathKey)
+        let fileExists: Bool
+        if let filePath = filePath, let containerURL = appGroupContainerURL {
+            let fileURL = containerURL.appendingPathComponent(filePath)
+            fileExists = FileManager.default.fileExists(atPath: fileURL.path)
+        } else {
+            fileExists = false
+        }
+
+        print("[ShareTarget] getShareExtensionDiagnostics shareExtensionLastStart=\(shareExtensionLastStart ?? "nil") sharedPhotoShareId=\(shareId ?? "nil") sharedPhotoFilePath=\(filePath ?? "nil") fileExists=\(fileExists)")
+
+        return [
+            "shareExtensionLastStart": shareExtensionLastStart ?? NSNull(),
+            "sharedPhotoShareId": shareId ?? NSNull(),
+            "sharedPhotoFilePath": filePath ?? NSNull(),
+            "fileExists": fileExists
+        ]
+    }
+
     /**
      * Check if shared photo ready flag is set
      * This flag is set by the Share Extension when image is ready

ios/App/TimeSafariShareExtension/ShareViewController.swift

@@ -14,6 +14,7 @@ class ShareViewController: UIViewController {
     private let sharedPhotoFileNameKey = "sharedPhotoFileName"
     private let sharedPhotoFilePathKey = "sharedPhotoFilePath"
     private let sharedPhotoShareIdKey = "sharedPhotoShareId"
+    private let shareExtensionLastStartKey = "shareExtensionLastStart"
     private let sharedImageFileName = "shared-image"
 
     /// Get the App Group container URL for storing shared files
@@ -22,6 +23,13 @@ class ShareViewController: UIViewController {
     }
 
     override func viewDidLoad() {
+        if let userDefaults = UserDefaults(suiteName: appGroupIdentifier) {
+            let timestamp = ISO8601DateFormatter().string(from: Date())
+            userDefaults.set(timestamp, forKey: shareExtensionLastStartKey)
+            userDefaults.synchronize()
+            print("[ShareTarget] shareExtensionLastStart=\(timestamp)")
+        }
+
         print("[ShareTarget] viewDidLoad started")
         super.viewDidLoad()
 

src/plugins/SharedImagePlugin.web.ts

@@ -4,7 +4,11 @@
  */
 
 import { WebPlugin } from "@capacitor/core";
-import type { SharedImagePlugin, SharedImageResult } from "./definitions";
+import type {
+  SharedImagePlugin,
+  SharedImageResult,
+  ShareExtensionDiagnostics,
+} from "./definitions";
 
 export class SharedImagePluginWeb
   extends WebPlugin
@@ -18,4 +22,13 @@ export class SharedImagePluginWeb
   async hasSharedImage(): Promise<{ hasImage: boolean }> {
     return { hasImage: false };
   }
+
+  async getShareExtensionDiagnostics(): Promise<ShareExtensionDiagnostics> {
+    return {
+      shareExtensionLastStart: null,
+      sharedPhotoShareId: null,
+      sharedPhotoFilePath: null,
+      fileExists: false,
+    };
+  }
 }

src/plugins/definitions.ts

@@ -7,6 +7,13 @@ export interface SharedImageResult {
   fileName: string;
 }
 
+export interface ShareExtensionDiagnostics {
+  shareExtensionLastStart: string | null;
+  sharedPhotoShareId: string | null;
+  sharedPhotoFilePath: string | null;
+  fileExists: boolean;
+}
+
 export interface SharedImagePlugin {
   /**
    * Get shared image data from native layer
@@ -20,4 +27,9 @@ export interface SharedImagePlugin {
    * Useful for quick checks before calling getSharedImage()
    */
   hasSharedImage(): Promise<{ hasImage: boolean }>;
+
+  /**
+   * Diagnostic snapshot of Share Extension startup and pending share state (iOS)
+   */
+  getShareExtensionDiagnostics(): Promise<ShareExtensionDiagnostics>;
 }